linux-kernel - Re: [PATCH net-next v2 2/2] net: macb: Add support for partial store and forward

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Message-ID: <ZFzo3X1L3JRa98HK@corigine.com>
Date:   Thu, 11 May 2023 15:08:45 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Pranavi Somisetty <pranavi.somisetty@....com>
Cc:     nicolas.ferre@...rochip.com, claudiu.beznea@...rochip.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, richardcochran@...il.com, linux@...linux.org.uk,
        palmer@...belt.com, git@....com, michal.simek@....com,
        harini.katakam@....com, radhey.shyam.pandey@....com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH net-next v2 2/2] net: macb: Add support for partial store
 and forward

On Thu, May 11, 2023 at 01:12:14AM -0600, Pranavi Somisetty wrote:
> When the receive partial store and forward mode is activated, the
> receiver will only begin to forward the packet to the external AHB
> or AXI slave when enough packet data is stored in the packet buffer.
> The amount of packet data required to activate the forwarding process
> is programmable via watermark registers which are located at the same
> address as the partial store and forward enable bits. Adding support to
> read this rx-watermark value from device-tree, to program the watermark
> registers and enable partial store and forwarding.
> 
> Signed-off-by: Maulik Jodhani <maulik.jodhani@...inx.com>
> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> Signed-off-by: Harini Katakam <harini.katakam@...inx.com>
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
> Signed-off-by: Pranavi Somisetty <pranavi.somisetty@....com>
> ---
> Changes v2:
> 
> 1. Removed all the changes related to validating FCS when Rx checksum offload is disabled.
> 2. Instead of using a platform dependent number (0xFFF) for the reset value of rx watermark,
> derive it from designcfg_debug2 register.
> 3. Added a check to see if partial s/f is supported, by reading the
> designcfg_debug6 register.
> ---
>  drivers/net/ethernet/cadence/macb.h      | 14 +++++++
>  drivers/net/ethernet/cadence/macb_main.c | 49 +++++++++++++++++++++++-
>  2 files changed, 61 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index 14dfec4db8f9..46833662094d 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -82,6 +82,7 @@
>  #define GEM_NCFGR		0x0004 /* Network Config */
>  #define GEM_USRIO		0x000c /* User IO */
>  #define GEM_DMACFG		0x0010 /* DMA Configuration */
> +#define GEM_PBUFRXCUT		0x0044 /* RX Partial Store and Forward */
>  #define GEM_JML			0x0048 /* Jumbo Max Length */
>  #define GEM_HS_MAC_CONFIG	0x0050 /* GEM high speed config */
>  #define GEM_HRB			0x0080 /* Hash Bottom */
> @@ -343,6 +344,11 @@
>  #define GEM_ADDR64_SIZE		1
>  
>  
> +/* Bitfields in PBUFRXCUT */
> +#define GEM_WTRMRK_OFFSET	0 /* Watermark value offset */
> +#define GEM_ENCUTTHRU_OFFSET	31 /* Enable RX partial store and forward */
> +#define GEM_ENCUTTHRU_SIZE	1
> +
>  /* Bitfields in NSR */
>  #define MACB_NSR_LINK_OFFSET	0 /* pcs_link_state */
>  #define MACB_NSR_LINK_SIZE	1
> @@ -509,6 +515,8 @@
>  #define GEM_TX_PKT_BUFF_OFFSET			21
>  #define GEM_TX_PKT_BUFF_SIZE			1
>  
> +#define GEM_RX_PBUF_ADDR_OFFSET			22
> +#define GEM_RX_PBUF_ADDR_SIZE			4
>  
>  /* Bitfields in DCFG5. */
>  #define GEM_TSU_OFFSET				8
> @@ -517,6 +525,8 @@
>  /* Bitfields in DCFG6. */
>  #define GEM_PBUF_LSO_OFFSET			27
>  #define GEM_PBUF_LSO_SIZE			1
> +#define GEM_PBUF_CUTTHRU_OFFSET			26
> +#define GEM_PBUF_CUTTHRU_SIZE			1
>  #define GEM_DAW64_OFFSET			23
>  #define GEM_DAW64_SIZE				1
>  
> @@ -718,6 +728,7 @@
>  #define MACB_CAPS_NEEDS_RSTONUBR		0x00000100
>  #define MACB_CAPS_MIIONRGMII			0x00000200
>  #define MACB_CAPS_NEED_TSUCLK			0x00000400
> +#define MACB_CAPS_PARTIAL_STORE_FORWARD		0x00000800
>  #define MACB_CAPS_PCS				0x01000000
>  #define MACB_CAPS_HIGH_SPEED			0x02000000
>  #define MACB_CAPS_CLK_HW_CHG			0x04000000
> @@ -1283,6 +1294,9 @@ struct macb {
>  
>  	u32			wol;
>  
> +	/* holds value of rx watermark value for pbuf_rxcutthru register */
> +	u16			rx_watermark;
> +
>  	struct macb_ptp_info	*ptp_info;	/* macb-ptp interface */
>  
>  	struct phy		*sgmii_phy;	/* for ZynqMP SGMII mode */
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 41964fd02452..07b9964e7aa3 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -2600,6 +2600,7 @@ static void macb_init_rings(struct macb *bp)
>  static void macb_reset_hw(struct macb *bp)
>  {
>  	struct macb_queue *queue;
> +	u16 watermark_reset_value;
>  	unsigned int q;
>  	u32 ctrl = macb_readl(bp, NCR);

Given the review of Conor Dooley of both patches in this series I think
there will be a v3.

Please consider adjusting the hunk above to move towards rather than
away from reverse xmas tree - longest line to shortest - for local
variable names.

That would be:

	u16 watermark_reset_value;
	struct macb_queue *queue;
	...

pw-bot: cr